/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.dx.rop.cst;

import com.android.dx.util.ToHuman;

/**
 * Base class for constants of all sorts.
 */
public abstract class Constant implements ToHuman, Comparable<Constant> {

	/**
	 * Returns {@code true} if this instance is a category-2 constant, meaning
	 * it takes up two slots in the constant pool, or {@code false} if this
	 * instance is category-1.
	 * 
	 * @return {@code true} iff this instance is category-2
	 */
	public abstract boolean isCategory2();

	/**
	 * Returns the human name for the particular type of constant this instance
	 * is.
	 * 
	 * @return {@code non-null;} the name
	 */
	public abstract String typeName();

	/**
	 * {@inheritDoc} This compares in class-major and value-minor order.
	 */
	public final int compareTo(Constant other) {
		Class clazz = getClass();
		Class otherClazz = other.getClass();

		if (clazz != otherClazz) {
			return clazz.getName().compareTo(otherClazz.getName());
		}

		return compareTo0(other);
	}

	/**
	 * Compare the values of this and another instance, which are guaranteed to
	 * be of the same class. Subclasses must implement this.
	 * 
	 * @param other
	 *            {@code non-null;} the instance to compare to
	 * @return {@code -1}, {@code 0}, or {@code 1}, as usual for a comparison
	 */
	protected abstract int compareTo0(Constant other);
}
